LOCATION WILLACY TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Udic Argiustolls
TYPICAL PEDON: Willacy fine sandy loam--cultivated.
(Colors are for dry soil unless otherwise
stated.)
Ap-=0 to 7 inches; dark grayish brown (10YR 4/2) fine sandy
loam, very dark grayish brown (10YR 3/2) moist; weak fine
granular structure; slightly hard; friable; mildly alkaline;
abrupt smooth boundary. (5 to 9 inches thick)
A--7 to 14 inches; dark grayish brown (10YR 4/2) fine sandy
loam, very dark brown (10YR 2/2) moist; weak fine granular and subangular blocky structure; slightly hard, friable; many fine
and very fine pores and root channels; mildly alkaline; clear
smooth boundary. (6 to 11 inches thick)
Bt1--14 to 19 inches; dark grayish brown (10YR 4/2) fine
sandy loam, very dark grayish brown (10YR 3/2) moist; moderate
medium prismatic breaking to weak fine subangular blocky
structure; slightly hard, friable; many fine pores and root
channels; patchy clay films on faces of prisms and in pores; many insect channels; mildly alkaline; clear wavy boundary. (4 to 9 inches thick)
Bt2--19 to 36 inches; brown (10YR 5/3) sandy clay loam, dark brown (10YR 4/3) moist; moderate medium prismatic breaking to
weak fine subangular blocky structure; hard, friable; many fine
pores and root channels; patchy clay films on faces of prisms and
in pores; mildly alkaline; clear wavy boundary. (13 to 20 inches thick)
Bk--36 to 42 inches; brown (10YR 5/3) sandy clay loam, dark
brown (10YR 4/3) moist; weak fine subangular blocky structure;
hard, friable; few films and threads and few soft bodies of
calcium carbonate; calcareous; moderately alkaline; clear wavy boundary. (4 to 11 inches thick)
Ck1--42 to 52 inches; pale brown (10YR 6/3) sandy clay loam, brown (10YR 5/3) moist; structureless; hard, friable; common fine
and very fine pores; 5 percent of soft bodies and weakly cemented concretions of calcium carbonate; calcareous; moderately
alkaline; clear wavy boundary. (8 ?o 16 inches thick)
Ck2--52 to 74 inches; pale brown (10YR 6/3) sandy clay loam, brown (10YR 5/3) moist; structureless; hard, friable; 4 percent
of soft bodies and strongly cemented concretions of calcium carbonate; calcareous; moderately alkaline.
TYPE LOCATION: Cameron County, Texas; 11.0 miles north 30
degrees west of Harlingen. In a cultivated field 135 feet north
and 215 feet west of the southeast corner of Block 16, Combes Subdivision, which is 1.0 mile east of U.S. Highway 77 on a
county road. (Intersection of county road and U.S. Highway 77 is
1.0 mile south of Willacy-Cameron County line.)
RANGE IN CHARACTERISTICS: Solum thickness ranges from 39 to 60 inches, and secondary lime occurs at depths of 36 to 50 inches
below the surface. Salinity ranges from none to as much as 8 mmhos/cm in areas irrigated with saline water.
The A horizon is very dark grayish brown (10YR 3/2), dark grayish brown (10YR 4/2), or grayish brown (10YR 5/2). Moist values are
less than 3.5. The A horizon is fine sandy loam, loam, or sandy
clay loam, and the reaction is neutral or mildly alkaline.
The B horizons are dark grayish brown (10YR 4/2), grayish brown
(10YR 5/2), dark brown (10YR 4/3), or brown (10YR 5/3). Some
pedons are light brownish gray (10YR 6/2) or pale brown (10YR
6/3) in the lower part. They are fine sandy loam or sandy clay
loam; clay content ranges from 18 to 33 percent. Structure of
the B horizons ranges from weak to moderately prismatic and subangular blocky. Reaction is neutral or mildly alkaline in the upper part of the B horizon and moderately alkaline in the lower part.
The C horizon is pale brown (10YR 6/3) very pale brown (10YR 7/3)
or light brownish gray (10YR 6/2). Visible accumulation of
calcium carbonate in the C horizon ranges from 3 to 5 percent by volume and remains relatively constant with depth.
Competing Series: There are no series in the same family.
Similar soils include Brennan, Clareville, Cuero, Czar, Duval,
Klump, Parasol, Ramadero, Stoneburg, and Tela series. Brennan
and Duval soils contain less than 1 percent organic matter in the epipedon. Clareville, Cuero, Czar, and Ramadero soils have
mollic epipedons thicker than 20 inches. Klump and Stoneburg
soils have mean annual soil temperatures less than 72 degrees F. Parasol soils have a difference of less than 9 degrees F. between mean summer and mean winter soil temperatures. Tela soils
contain secondary lime at depths less than 34 inches.
GEOGRAPHIC SETTING: Willacy soils occur in nearly level coastal terraces and deltas with slope gradients mostly less than 2
percent but range up to about 5 percent along local drainageways. The soil formed in alkaline, loamy sediments 10 feet or more
deep. The climate is dry subhumid. Average annual precipitation ranges from 26 to 34 inches and the mean annual air temperature ranges from 72 to 74 degrees F. Annual Thornthwaite P-E index
ranges from 28 to 44.
GEOGRAPHICALLY ASSOCIATED SOILS: These include
Hargill,
Hidalgo,
Racombes, and
Raymondville series. Hargill soils have sola more
than 60 inches thick. Hidalgo and Raymondville soils are
calcareous throughout and in addition, Raymondville soils have
more than 35 percent clay in the 10- to 40-inch control section. Racombes soils have mollic epipedons more than 20 inches thick.
All these soils occur on similar surfaces.
Drainage and Permeability: Well drained; medium runoff; moderate permeability. Under irrigation, seasonal watertables accumulate
5 to 8 feet below the surface.
USE AND VEGETATION: Mostly cultivated and mostly irrigated. Few areas in native rangeland. Use for wide variety of vegetables, citrus, cotton, grain sorghums, and flax. In rangeland, the
grasses are mostly fourflower trichloris, Arizona cottontop, lovegrass tridens, plains bristlegrass, hooded windmillgrass, and hairy grama. Woody vegetation consists of mesquite and Texas
ebony trees, and spiny hackberry, blackbrush, catclaw, lote,
brazil, and pricklypear.
DISTRIBUTION AND EXTENT: Mainly within the lower Rio Grande
Plain and Gulf Coast Prairies in southern Texas. Possibly in
Mexico. Series is of moderate extent comprising about 90,000
acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Hidalgo County, Texas; 1925.
REMARKS: Limited laboratory data available from ARS-SCS
cooperative study.